A286474 Compound filter: a(n) = 4*A032742(n) + (n mod 4), a(1) = 1.

1, 6, 7, 8, 5, 14, 7, 16, 13, 22, 7, 24, 5, 30, 23, 32, 5, 38, 7, 40, 29, 46, 7, 48, 21, 54, 39, 56, 5, 62, 7, 64, 45, 70, 31, 72, 5, 78, 55, 80, 5, 86, 7, 88, 61, 94, 7, 96, 29, 102, 71, 104, 5, 110, 47, 112, 77, 118, 7, 120, 5, 126, 87, 128, 53, 134, 7, 136, 93, 142, 7, 144, 5, 150, 103, 152, 45, 158, 7, 160, 109, 166, 7, 168, 69, 174, 119, 176, 5, 182, 55

Offset: 1

Author

Antti Karttunen, May 11 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A032742, A285729, A286472, A286473, A286475, A286476.

Programs

Mathematica

Table[If[n == 1, 1, 4 (Divisors[n][[-2]]) + Mod[n, 4]], {n, 91}] (* Michael De Vlieger, May 12 2017 *)

Python

from sympy import divisors, primefactors
def a(n): return 1 if n==1 else 4*divisors(n)[-2] + n%4 # Indranil Ghosh, May 12 2017

Scheme

(define (A286474 n) (if (= 1 n) n (+ (* 4 (A032742 n)) (modulo n 4))))

Formula

a(1) = 1, for n > 1, a(n) = 4*A032742(n) + (n mod 4).